- added

git-svn-id: http://moon:8086/svn/matlab/trunk@128 801c6759-fa7c-4059-a304-17956f83a07c

equalizer/boost.m

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+function [B,A] = boost(fs, fc, bw, gain, P);
+%BOOST - Design a boost filter at given gain, center
+%        frequency fc, bandwidth bw, and sampling rate fs
+%        (default = 1).
+%
+% J.O. Smith 11/28/02
+% Reference: Zolzer: Digital Audio Signal Processing, p. 124
+
+Q = fs/bw;
+wcT = 2*pi*fc/fs;
+
+K=tan(wcT/2);
+V=gain;
+
+b0 =  1 + V*K/Q + K^2;
+b1 =  2*(K^2 - 1);
+b2 =  1 - V*K/Q + K^2;
+a0 =  1 + K/Q + K^2;
+a1 =  2*(K^2 - 1);
+a2 =  1 - K/Q + K^2;
+A(1,:) = [a0 a1 a2] /a0;
+B(1,:) = [b0 b1 b2] /a0;
+
+if nargout==0
+  freqz(B(1,:),A(1,:));
+  title('Boost Frequency Response')
+end
+